A non-limiting example of such an anchoring member is a projecting helical screw which axially extends from the body of the medical device and is intended to penetrate and screw into a cardiac tissue at the implantation site. Other non-limiting examples of anchoring members include needles, hooks, barbs, etc. that penetrate the tissue to permanently secure the medical device.
In a particular embodiment, the device is a capsule implanted in a heart chamber (ventricle, atrium or even arterial left cardiac cavity). The capsule may be autonomous, hereinafter referred to as an “autonomous capsule” or “leadless capsule”. These autonomous capsules are devoid of any physical connection to an implantable main device (such as the housing of a stimulation pulse generator) or non-implantable device (external peripheral device such as a programmer or a monitoring device for remote monitoring of the patient), and for this reason, they are referred to as “leadless capsules” to distinguish them from electrodes or sensors disposed at the distal end of a conventional lead, which is traversed throughout its length by one or more conductors galvanically connecting the electrode or the sensor to a generator connected to an opposite, proximal end of the lead.
In another particular embodiment, a method is disclosed of delivering or installing, at a chosen implantation site, other types of medical devices, including, for example, stimulation leads in the form of a tubular body having at its distal end an anchoring member for anchoring to a heart wall and an active portion provided with detection/stimulation electrodes, and at its proximal end, mechanical and electrical means for connection to a generator housing, where the generator housing is implanted remotely from the site of application of the pulses. The present disclosure can also be applied to other types of implantable devices, for example, in capsules intended for deliver in situ an active pharmacological agent.
In the case wherein the leadless capsules are endocardial capsules (that is to say capsules to be fixed to the inner wall of a ventricular or atrial cavity, as opposed to epicardial capsules fixed to the external wall of the heart), the implantation constraints are greater due to the approach path, which involves going through the peripheral venous system and then leading under fluoroscopy the capsule to the chosen implantation site, both in an accurate and secure manner. It is only once the site is reached and the capsule is firmly anchored in the heart wall that the operator can “release” the capsule, that is to say, can separate it from the implantation accessory.
EP 2 818 201 A1 (Sorin CRM SAS) describes a system of in situ implantation of an intracardiac capsule with its accessory. The autonomous capsule comprises a cylindrical tubular body provided at its distal end with an anchoring member adapted to penetrate a tissue wall of a cavity of the heart. The remotely steerable implantation accessory comprises a catheter with an internal lumen, extended at its distal end by a protective tubular tip defining an interior volume adapted to receive the capsule, the disconnectable means being provided for supporting and guiding the capsule until the capsule is implanted at an implantation site. The implantation accessory further comprises a sub-catheter movably housed within the lumen of remotely steerable catheter. The sub-catheter and the capsule can be deployed telescopically relative to the catheter between a retracted position wherein the capsule and its anchoring means are completely housed inside the tubular protective tip, and a deployed position wherein the capsule is out to the tubular protective tip and is carried by the distal end of the sub-catheter. Finally, the distal end of the sub-catheter and the proximal region of the capsule are provided with securing means in translation and in mutual rotation, these securing means being disconnectable to drop the capsule once in place.
The EP 2 818 201 A1 document also describes the constraints related to this type of implantation, and the benefits of such a system. The EP 2 818 201 A1 document can be referred to as needed and is hereby incorporated by reference in its entirety.
EP 2394 695 A1 (Sorin CRM SAS) describes a similar implantation accessory but not implementing a telescopic sub-catheter. The capsule is carried by the tip, and coupled thereto by a helical screw system. The implantation is made by bringing into contact the assembly formed by the tip with the capsule inside with the cardiac tissue and anchoring the capsule to the tissue. After anchoring the capsule, a rotational movement imparted to the accessory simultaneously backs the tip and decouples the capsule. As a precaution, a wire or thread connects the tip to the capsule in case it would be necessary to re-intervene to explant the capsule, for example, if the originally chosen site was unsatisfactory after an electrical test, and another site must be found. The wire or thread then guides the tip until it reaches the capsule on which it may then be coupled again to allow explantation of the capsule. The EP 2394 695 A1 document is hereby incorporated by reference in its entirety.
Although this type of device is generally satisfactory, its endovenous and endocardial handling may present some risks because of its size, its form factor, the effort required to transfer power, etc. These risks may include: alteration of venous and/or cardiac tissue, alteration of the tricuspid valve or even cardiac perforation. Indeed, the thickness of the heart wall in close proximity to the classical target (the apex) is of the order of 1 to 2 mm only, and according to the methods of implantation, the doctor may need to directly touch this thin wall with the protective tip itself, operated remotely (by femoral approach) via a powerful remotely steerable catheter, with the transmission of torque and/or a significant axial push.
In addition, the use of such material is relatively undeveloped, as practitioners are instead accustomed more flexible stimulation or defibrillation leads.